As broadcast partners indicate they're ravenous for more NRL expansion - and soon - Marshall says his homeland is "crying out for a second team".
The league has pledged to work towards a 20th team as soon as 2029, as part of a seven-year, $5.3 billion broadcast deal signed on Tuesday.
While noting the decision is out of his pay grade, the Kiwis legend argued another club would help strengthen the foothold his sport has in a country where rugby league's rival code dominates.
"The impact the Warriors are having on New Zealand having success in rugby league is massive. You can't underestimate that," Marshall said.
"Especially with the young kids coming through and choosing rugby or league, I think a second team would be great for them."
The Wests Tigers coach is no stranger to tension between the codes on the other side of the Tasman, having appeared six times for Super Rugby's Auckland-based Blues in 2014, before diving back into rugby league.
The former halfback and five-eighth, who played 31 rugby league Tests for New Zealand, nevertheless downplayed the contest with union.
"I don't see it as competition, I think there's a respect between both codes. I'm not trying to compete against them," he said.
Perth Bears will enter the NRL in 2027 followed in 2028 by the PNG Chiefs.
Brisbane's western corridor, central Queensland and Christchurch have emerged as the leading contenders for the next wave of expansion.
The league will need to make a call soon to meet a 2029 deadline, Australian Rugby League Commission chair Peter V'landys flagged on Tuesday.
"I need to talk to the clubs, we need to start planning because you need to give them as much lead time as possible," V'landys said while announcing the broadcast deal.
"The priorities for us after this is globalisation."
Marshall would not be drawn on a hypothetical State of Origin-style clash on the other side of the Tasman.
"I don't know what you're dragging me into," he said on Wednesday.
"Might have to be Auckland against the rest."
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